Biomedical subjects

Yelda Ozsunar

Publications and source records attributed to Yelda Ozsunar.

14 recordsLinked to original sources

PubMed2005

Surgical pinealectomy accelerates intervertebral disc degeneration process in chicken.

Despite the importance of intervertebral disc (IVD) degeneration both in research and clinical practice, the underlying biological mechanism of this phenomenon remains obscure. The current study investigated the effects of neonatal pinealectomy on the development of IVD degeneration process in chicken. Thirty chicks (3 days of age) were divided into two equal groups: unoperated controls (Group X) and pinealectomized chicks (Group Y). Pinealectomies were performed at the age of 3 days. At the age of 8 weeks, magnetic resonance imaging examination of one animal in each experimental group was taken. At the end of the study, serum melatonin level was determined by using ELISA method and histopathological or biochemical examination of specimens from all subjects was done. The results of biochemical analyses were compared using Mann-Whitney U test, whereas The Chi-square test was adopted for the histological findings. In this study, the serum melatonin levels in Group Y were significantly lower than those in Group X (P < 0.001). Similarly, scoliosis was developed in 14 out of 15 (93%) in Group Y. Hydroxyproline content of IVD tissue was high in Group Y compared with the values in Group X, although there was no significant difference. Histologically, an appearance of normal IVD was observed in Group X, while the presence of a degenerated IVD was observed in Group Y. From the results of the current study, it is evident that surgical pinealectomy in new-hatched Hybro Broiler chicks has a significant effect on serum melatonin level as well as on the development of IVD degeneration and spinal malformation. In the light of these results from present animal study, melatonin may play a role in the development of IVD degeneration in human beings, but this suggestion need to be validated in the human setting.

Animals↗

PubMed2005

Pseudolesions of left liver lobe during helical CT examinations: prevalence and comparison between unenhanced and biphasic CT findings.

OBJECTIVE: Localized low attenuated areas (pseudolesions) in the medial segment of left liver lobe are not rarely seen in the screening of abdomen using helical CT. The purpose of this study was to determine the prevalence of pseudolesions in the routine helical CT of abdomen and to evaluate the morphologic and enhancement features of pseudolesions in the unenhanced and enhanced CT examinations. MATERIALS AND METHODS: We retrospectively evaluated 333 contrast enhanced abdominal CT examination of 328 patients with no known liver disease, to detect the presence of pseudolesion of liver. In the presence of unenhanced and arterial phase examinations, these images were also analyzed. The imaging criteria for pseudolesion of liver was localized low attenuated area with geometric, ovoid or nodular shaped and with no mass effect adjacent to the falciform ligament, gallbladder, or porta hepatis. Previous CT, CTAP and MR examinations were also reviewed to understand the evolution of pseudolesion in patients in whom a pseudolesion was detected in the portal phase of helical CT examination. RESULTS: We identified a pseudolesion in the 65 (19.8%) of 328 patients in portal phase of helical CT examinations. Pseudolesions were identified in the medial segment of left liver lobe adjacent to falciform ligament in the 92.8% of patients, both sides of falciform ligament in the 1.5% of patients, adjacent to porta hepatis in the 3% of patients and adjacent to gallbladder 3% of patients. These lesions had triangular shape in the 66.1% of patients, ovoid shape in the 18.6% of patients, and nodular shape in the 15.3% of patients. Unenhanced, arterial and portal phase images were exist in the 50.7% of 65 patients. The pseudolesions were not identified on the unenhanced images in the 75.7% of patients and on the arterial phase images in the 55.6% of patients. CONCLUSION: Pseudolesions around the falciform ligament are not rarely seen in the routine helical CT examination of liver and abdomen. The pseudolesions are more encountered in the portal phase of helical CT examination. These lesions seem to be likely focal fatty infiltration or perfusion defect due to venous supply variation or both. Nodular shaped pseudolesions may be interpreted as true tumors and further study may require for differential diagnosis.

Adult↗

PubMed2005

Sponge-induced granuloma ("gauzoma") as a complication of posterior lumbar surgery.

A 45-year-old woman presented with complaints of low back pain and sciatica on the left persisting for 2 years. She had undergone left hemilaminectomy and discectomy for L4-5 intervertebral disc herniation at another medical center. Spinal computed tomography and magnetic resonance (MR) imaging revealed a mass lesion in the posterior paravertebral region. The mass was hypointense with ring enhancement on the T(1)-weighted images and hyperintense on the T(2)-weighted images. Surgery found a retained sponge within the paraspinal mass cavity which was removed totally. Foreign-body granuloma ("gauzoma") induced by forgotten sponge material is not an unusual complication of posterior lumbar surgery and should be considered as a potential cause in cases of surgical wound infections. MR imaging is essential to achieve the correct differential diagnosis.

Diskectomy↗

PubMed2005

Transient hepatic attenuation differences at biphasic spiral CT examinations.

Transient hepatic attenuation difference (THAD) is a perfusion disorder that can sometimes be observed in hepatic arterial phase of a biphasic spiral CT examination. The involved site of liver by THAD appears as an area of high attenuation on the hepatic arterial phase image and returns to normal attenuation on portal venous phase image. The knowledge of the shape, distribution and causes of THAD is essential to differentiate the THAD from other pathologies such as neoplasm.

Budd-Chiari Syndrome↗

PubMed2004

MRI measurements of water diffusion: impact of region of interest selection on ischemic quantification.

OBJECTIVE: To investigate the effect of ADC heterogeneity on region of interest (ROI) measurement of isotropic and anisotropic water diffusion in acute (< 12 h) cerebral infarctions. METHODS AND MATERIALS: Full diffusion tensor images were retrospectively analyzed in 32 patients with acute cerebral infarction. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured in ischemic lesions and in the corresponding contralateral, normal appearing brain by using four ROIs for each patient. The 2 x 2 pixel square ROIs were placed in the center, the lateral rim and the medial rim of the infarction. In addition, the whole volume of the infarction was measured using a free hand method. Each ROI value obtained from the ischemic lesion was normalized using contralateral normal ROI values. RESULTS: The localization of the ROIs in relation to the ischemic lesion significantly affected ADC measurement (P < 0.01, using Friedman test), but not FA measurement (P = 0.25). Significant differences were found between ADC values of the center of the infarction versus whole volume (P < 0.01), and medial rim versus whole volume of infarction (P < 0.001) with variation of relative ADC values up to 11%. The differences of absolute ADC for these groups were 22 and 23%, respectively. The lowest ADC was found in the center, followed by medial rim, lateral rim and whole volume of infarction. CONCLUSION: ADC quantification may provide variable results depending on ROI method. The ADC and FA values, obtained from the center of infarction tend to be lower compared to the periphery. The researchers who try to compare studies or work on ischemic quantification should be aware of these differences and effects.

Adolescent↗

PubMed2004

Glial tumor grading and outcome prediction using dynamic spin-echo MR susceptibility mapping compared with conventional contrast-enhanced MR: confounding effect of elevated rCBV of oligodendrogliomas [corrected].

BACKGROUND AND PURPOSE: The MR imaging characteristics of oligodendrogliomas and astrocytomas on spin-echo (SE), echo-planar relative cerebral blood volume (rCBV) maps, to our knowledge, have not previously been emphasized. We compared the specificity of SE rCBV mapping with that of conventional, contrast material-enhanced MR imaging in differentiating high- from low-grade glial tumors and in predicting survival of patients with these lesions. METHODS: Thirty consecutive adult patients with suspected gliomas underwent conventional and rCBV MR imaging. Representative maximal rCBV regions of interest were chosen from each lesion. Resultant values were normalized to those of corresponding, contralateral, uninvolved regions. These normalized CBV (nCBV) values were correlated with degree of contrast enhancement, histopathologic tumor grade, and survival. RESULTS: Twenty-two patients had astroctyomas and eight had oligodendrogliomas. With an nCBV cutoff ratio of 1.5, 13 of 13 high-grade astrocytomas were correctly categorized, three of which did not enhance. Seven of nine low-grade astrocytomas were correctly classified by their nCBV values, including one enhancing lesion. Of eight oligodendrogliomas, four of four high-grade and two of four low-grade tumors had elevated nCBV values; two low-grade oligodendrogliomas enhanced, one with nCBV greater than 1.5 and one with nCBV less than 1.5. In 19 patients with astrocytoma for whom survival data were available, correlation with survival was better for nCBV (mean survival 91 +/- 14 months for nCBV < 1.5 versus 24 +/- 27 months for nCBV > 1.5, P <.0001) than for enhancement (mean survival 61 +/- 35 months without enhancement versus 22 +/- 29 months with enhancement, P =.03). CONCLUSION: Elevated SE rCBV was a sensitive, but not specific, marker for high-grade histopathology: all high-grade tumors had nCBV foci values greater than 1.5. No tumor with nCBV region of interest less than 1.5 was high grade (100% predictive value for excluding high grade). Degree of nCBV elevation was a stronger predictor of both tumor grade and survival than was degree of enhancement. A significant proportion of low-grade glial neoplasms, most notably oligodendrogliomas, may display high rCBV foci not reflective of high-grade histopathology.

Adolescent↗

PubMed2004

Diffusion tensor imaging as potential biomarker of white matter injury in diffuse axonal injury.

BACKGROUND AND PURPOSE: Multiple biomarkers are used to quantify the severity of traumatic brain injury (TBI) and to predict outcome. Few are satisfactory. CT and conventional MR imaging underestimate injury and correlate poorly with outcome. New MR imaging techniques, including diffusion tensor imaging (DTI), can provide information about brain ultrastructure by quantifying isotropic and anisotropic water diffusion. Our objective was to determine if changes in anisotropic diffusion in TBI correlate with acute Glasgow coma scale (GCS) and/or Rankin scores at discharge. METHODS: Twenty patients (15 male, five Female; mean age, 31 years) were evaluated. Apparent diffusion coefficients (ADCs) and fractional anisotropy (FA) values were measured at multiple locations and correlated with clinical scores. Results were compared with those of 15 healthy control subjects. RESULTS: ADC values were significantly reduced within the splenium (Delta18%, P =.001). FA values were significantly reduced in the internal capsule (Delta14%; P <.001) and splenium (Delta16%; P =.002). FA values were significantly correlated with GCS (r = 0.65-0.74; P <.001) and Rankin (r = 0.68-0.71; P <.001) scores for the internal capsule and splenium. The correlation between FA and clinical markers was better than for the corresponding ADC values. No correlation was found between ADC of the internal capsule and GCS/Rankin scores. CONCLUSION: DTI reveals changes in the white matter that are correlated with both acute GCS and Rankin scores at discharge. DTI may be a valuable biomarker for the severity of tissue injury and a predictor for outcome.

Adult↗

PubMed2004

Evolution of water diffusion and anisotropy in hyperacute stroke: significant correlation between fractional anisotropy and T2.

BACKGROUND AND PURPOSE: We hypothesized that, in acute cerebral ischemic stroke, anisotropic diffusion increases if T2 signal intensity is not substantially elevated and decreases once T2 hyperintensity becomes apparent. Our purpose was to correlate fractional anisotropy (FA) measurements with the clinical time of stroke onset, apparent diffusion coefficients (ADC), and T2 signal intensity. METHODS: Tensor diffusion-weighted images (DWIs) of 25 patients were obtained within 12 hours of symptom onset. Trace DWIs, ADCs, FAs, and echo-planar T2-weighted images (T2WI) were generated. Stroke and contralateral normal volumes of interest (VOIs) were outlined on DWIs and projected onto the inherently coregistered ADC map, FA map, and echo-planar T2WI. Mean signal intensity of the ischemic and contralateral normal VOIs were compared for relatives change in ADC, FA, and signal intensity on T2WIs. RESULTS: A significant negative correlation was observed between FA and T2 signal-intensity change (r = -0.61, P =.00009). A trend of correlation between FA signal intensity and time of onset were found (r = -0.438, P =.025). No significant correlation was found between ADC and FA values (r = -0.302, P =.134). The mean ADC reduction in the ipsilateral ischemic volume was 31% +/- 11 compared with the contralateral normal side. CONCLUSION: Change in FA is inversely correlated with T2 signal intensity and, to a lesser extent, the time of onset, but it is not well correlated with ADC values in the acute stage.

Acute Disease↗

PubMed2003

Partial preoperative reduction of inguinal hernia through compression with an ultrasound transducer.

Sonography and CT are effective tools in early diagnosis of asymptomatic inguinal hernia. Sonography can be used not only for the diagnosis of hernia but also for its treatment. Real-time sonographically guided hernia reduction may avoid tissue damage that can arise from misguided compression. We report a unique case in which an incarcerated omental hernia in a 50-year-old woman was diagnosed and subsequently reduced via compression with an ultrasound transducer.

Female↗

PubMed2003

PACS utilization in radiologic research.

RATIONALE AND OBJECTIVES: The authors investigated patterns of utilization of the digital picture archiving and communication system (PACS) in radiologic publications in order to ascertain whether there may be a correlation between PACS use and demographic/cultural factors such as geographic location, radiologic specialization, and use of advanced radiologic technologies. MATERIALS AND METHODS: A total of 1,037 articles in 22 randomly selected issues of AJR: American Journal of Roentgenology and of Radiology (1999-2001) were reviewed for the rate of PACS use and the type of PACS used. Articles for which PACS use or nonuse was established were further classified according to originating continent or region, imaging modality, study design (whether retrospective or prospective), and the use of advanced radiologic technology. The use of a PACS was then correlated with these factors. The data were recorded and statistics were prepared by means of statistical software. The nonparametric (chi2) test also was run by using this software. RESULTS: PACS had been used and reported in the preparation of 225 of the 1,037 articles. The type of PACS used was mini PACS (eg, systems using digital imaging and communications in medicine [DICOM] protocols or precursors) in 55 (24%) and department- or hospital-wide PACS in 161 (72%). Most of the articles for which use of a PACS was reported had originated in North America (60%), Europe (22%), or Asia (14%). PACS were used in almost half of retrospective studies and in one-fourth of prospective studies (P < .01). A low correlation was found between utilization of PACS and use of other advanced technologies. CONCLUSION: Although PACS were utilized in the preparation of a substantial proportion of articles published in the two major radiology journals, there was a great disparity in the rate of PACS use among world regions. The proportion of studies originating in North America for which a PACS was used was nearly three times the number of similar studies originating in Europe, and more than four times the number originating in Asia.

Chi-Square Distribution↗

PubMed2003

Subthalamic nucleus tumor causing hyperphagia--case report.

A 42-year-old woman with locally advanced breast cancer developed headache just after completing adjuvant chemotherapy. Magnetic resonance imaging revealed a mass located in the left subthalamic nucleus (STN) and involving the posterior part of the thalamus and the hypothalamus. The patient refused a radiologically guided biopsy and gamma knife treatment was not financially possible. Palliative whole brain radiotherapy with hormonal therapy was administered. The patient gained 19 kg body weight during 4 months follow up because of hyperphagia. This solitary tumor, either a breast cancer metastasis or a primary tumor, involving the STN is extremely unusual.

Adult↗

PubMed2003

Assessing tissue viability with MR diffusion and perfusion imaging.

BACKGROUND AND PURPOSE: Diffusion- (DW) and perfusion-weighted (PW) MR imaging reflect neurophysiologic changes during stroke evolution. We sought to determine parameters that distinguish regions of brain destined for infarction from those that will survive despite hypoperfusion. METHODS: DW and PW images were obtained in 30 patients at 1-12 hours after symptom onset. Relative cerebral blood volume (rCBV), flow (rCBF), mean transit time (MTT), apparent diffusion coefficient (ADC), DW image signal intensity, and fractional anisotropy (FA) lesion-contralateral normal region ratios were obtained in the following regions: 1) infarct core with hyperintensity on DW image, abnormality on rCBF and MTT images, and follow-up abnormality; 2) infarcted penumbra with normal DW image, abnormal rCBF and MTT images, and follow-up abnormality; and 3) hypoperfused tissue that remained viable, with normal DW image, abnormal rCBF and MTT images, and normal follow-up. RESULTS: rCBF ratios for regions 1, 2, and 3 were 0.32 +/- 0.11, 0.46 +/- 0.13, and 0.58 +/- 0.12, respectively, and were significantly different. DW image intensity and ADC ratios were significantly different among all regions, but were more similar than rCBF ratios. rCBV and FA ratios were not significantly different between regions 2 and 3. No MTT ratios were significantly different. No region of interest with an rCBF ratio less than 0.36, an rCBV ratio less than 0.53, an ADC ratio less than 0.85, a DW image intensity ratio greater than 1.23, or an FA ratio greater than 1.10 remained viable. No region of interest with an rCBF ratio greater than 0.79 infarcted. CONCLUSIONS: Differences among mean ratios of three regions investigated were greatest for the rCBF ratio. The rCBF ratio may be the most useful parameter in differentiating viable tissue that is likely to infarct without intervention, from tissue that will survive despite hypoperfusion. ADC, DW intensity, FA, and rCBV ratios may provide adjunctive information.

Adult↗

PubMed2003

[Status of international radiological publications and archive utilization in Turkey].

PURPOSE: To investigate the use of radiological technology and archive utilization in two sampled international radiological journals and radiology clinics in Turkey, and to explore the impact of these findings on radiological publications. MATERIALS AND METHODS: Randomly selected 22 issues of AJR and Radiology, 1037 articles in total, were reviewed. The type of article, radiological technique, country of origin, use of advanced technology and archiving were defined for each article. Additionally, a questionnaire, investigating implementation of various radiological devices, archiving and their technical features, was posted to the chairmen of the radiology departments in Turkey. RESULTS: Most of the articles (61.4%) originated in US. Studies from Turkey constituted 0.9% of the articles. This ratio was 2% for France, which has almost the same population as Turkey. Magnetic resonance imaging was used in 27.4% of cases. Based on our definition criteria, advanced technology and archiving were used in 19% and 32%, respectively. Data returns of the questionnaire were obtained from 17 of 45 (38%) radiology clinics. Responding clinics had conventional radiography, B mode ultrasound and conventional computed tomography. Archiving of all radiological examinations, excluding plain radiography, was performed in one center while only interesting radiological images and variations were stored in 8 departments. Implementation of archiving was reported sufficient in three clinics, partly sufficient in ten clinics and insufficient in four clinics. Archiving was performed by medical doctors in most of the cases (53%). The leading problems of archiving were technical and economical insufficiencies (82%). CONCLUSION: Archiving is more commonly required than utilization of advanced technology for international radiological publications. The rate of articles originating from Turkey was lower compared to some countries having the same population as Turkey. The lack of sufficient technical infrastructure and shortage of staff may be important reasons for such differences.

Bibliometrics↗

PubMedDate not supplied

Resistive index measurement of native hemodialysis arteriovenous fistula feeding artery as a predictor for fistula dysfunction.

The aim of the present study was to evaluate resistive index (RI) in the feeding artery of the functioning and dysfunctioning arteriovenous fistulas (AVFs). Measurement of RI in the feeding artery using Doppler ultrasound was performed in 48 patients on hemodialysis. Twenty-seven upper arm AVFs and 21 radiocephalic AVFs were studied. The patients were categorized into three groups according to clinical function: group 1, AVFs with normal function (n = 21); group 2, AVFs with abnormal clinical function (reduced pump flow) (n = 20); and group 3, AVFs with abnormal clinical function (increased venous pressure) (n = 7). Resistive index measurements and morphologic changes were compared between functioning and dysfunctioning AVFs. Increased RI values were detected in the AVFs with reduced pump flow. The average RI values of feeding artery were 0.47 +/- 0.07 in group 1, 0.67 +/- 0.18 in group 2, and 0.49 +/- 0.05 in group 3. Two brachial artery aneurysms, one brachial artery pseudoaneurysm, ten venous stenoses, and six venous thromboses were detected in the AVFs with diminished pump flow (18/20 patients, 90%). Both increased RI values and vascular complications were detected by Doppler ultrasound in the patients with reduced pump flow during dialysis. This study shows that Doppler ultrasound examination of AVF feeding artery may provide useful data on morphologic and functional characteristics of AVF.

Adult↗